1: What is evidence-based policing?

This chapter outlines the origins of evidence-based policy and explains the limitations of the traditional ‘craft’ based approach to policing. It argues that experience, while having its merits, is susceptible to inaccurate beliefs, subjective opinions, and systematic bias. The chapter also outlines the scientific method, a set of steps necessary to conduct research in a scientific manner, before defining evidence-based policing and outlining the key threads of the various definitions available. The chapter continues with a flowchart to estimate the level of evidence-based adoption in a police agency. A summary of the need for evidence-based policing concludes the chapter.

Glossary terms in this chapter

Confirmation bias: Our human tendency to interpret information and evidence in a way that supports our existing beliefs.

Natural experiments: Policy situations that occur in the real world without any researcher intervention that provide an opportunity for observational study.

Standard model of policing: This involves random patrol across all parts of a jurisdiction, rapid response to crime when it happens, and a focus on criminal investigation.

Evidence-based policing: An approach where police officers and staff create, review, and use the best available evidence to inform and challenge policies, practices, and decisions.

Personal experience: Acquired over time, this is the act of reflecting on the outcomes of actions taken in similar circumstances to the one currently faced. In other words, we think back to how we acted in similar events and adjust our current behavior to achieve a better outcome.

Scientific evidence: Scientific evidence is the accumulated wisdom from systematic studies and observations that can help a policy maker reach a conclusion about a policy choice. Scientific evidence (at least in the context of this book) is proof that can support a position or claim of effectiveness.

Positivists: Positivists lean towards the ‘science’ in ‘social science’ and favor quantitative methods to understand the laws and principles that influence human behavior and our social trends.

Interpretivists: Interpretivists tends towards the ‘social’ in ‘social science’, arguing that people are more individualistic and respond differently to the same stimuli and societal forces.

Clinical expertise: A combination of experience, training, and judgement exercised in a practical or professional setting.

Culture of curiosity: A policing culture that accepts some doubt and a willingness to question the current orthodoxy of policing.

Evidence-based policing: An approach where police officers and staff create, review, and use the best available evidence to inform and challenge policies, practices, and decisions.

Additional information and links

The copper’s nose

The book starts with an overview of the gruesome murders committed by Zahid Younis in east London. Further information on the case can be found at the BBC and Sky News.

In the discussion around the "craft" of policing, there is a good open-source overview of the merits and limitations of police craft in relation to a more scientific approach written by James Willis and published by the National Policing Institute, called Improving Police: What’s Craft Got to Do with It?

The origins of evidence-based policy

Northwestern University has a nice resource page that covers an overview of the Cambridge-Somerville Youth Study.

‘How we’ve always done it’

George Mason University's Center for Evidence-Based Crime Policy has a handy overview of the Standard Model of Policing that can add information to the book chapter.

Defining evidence-based policing

Gary Cordner's evidence-based policing in 45 small bytes is a worthwhile read, sponsored by the National Institute of Justice.

A pivotal work in the medical field is the outline of evidence-based medicine from Sackett and colleagues, published as Sackett, D. L., Rosenberg, W. M., Gray, J. A., Haynes, R. B., & Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn't. British Medical Journal, 312(7023), 71-72.

An outline of the scientific method

There is an reasonable summary video here about the scientific process, once you can get past the idea of ticks landing on you and taking a bite. It even includes a discussion of confirmation bias, one of the significant problems with human acceptance of evidence (if it contradicts their expectations or wishes).

It is also worth not getting hung up on the exact model of the scientific method. For example, some people have six steps to the scientific method, while others have five, and you can find other models with seven steps. As long as the core tenets of using data and observation, allied with logical thought and reason, are used to draw conclusions about the world, then you are probably on the correct track. And of course, I lean towards a seven step model as you find in my chapter ;-)

Reducing Crime podcast episode

Renee Mitchell (#13)

Dr. Renee Mitchell is a sergeant in the Sacramento police department, California, and a co-founder and current president of the American Society of Evidence-Based Policing. In a wide-ranging chat, we explore the myriad ways research can help 21st century policing. We also cover her Sacramento Hot Spots Experiment, how policing research is like following the white rabbit from Alice in Wonderland, Critical Incident Stress Debriefing and its lack of evidence base, "Make it stop" policing, and the lack of science around police-involved shootings.